Nearly half of Slovakia's entire population took Covid-19 swabs on Saturday, the first day of two-day nationwide testing the government hopes will help reverse a fast rise in infections without a hard lockdown.
The scheme, a first in a country of comparable size, is being watched by other nations looking for ways to slow the virus spread and avoid overwhelming their health systems.
Defence Minister Jaroslav Nad said on Sunday 2.58 million Slovaks took the test on Saturday, and 25,850 or 1% tested positive and must go into quarantine.
The European Union country has 5.5 million people and aims to test as many as possible, except for children under 10.
More than 40,000 medics and support teams of soldiers, police, administrative workers and volunteers staffed around 5,000 sites to administer the antigen swab tests.
The testing was free and voluntary, but the government will impose a lockdown on those who do not participate, including a ban on going to work.
Prime Minister Igor Matovic said he was apologising for putting pressure on people to take part, but said the requirement was justified.
"Freedom must go together with responsibility toward those who ... are the weakest among us, oncology patients, old people, people with other diseases," he told a news conference.
Slovakia suffered only thousands of cases in the spring and summer after swiftly imposing restrictions.
But infections have soared in the past weeks, raising concern the country may follow neighbouring the Czech Republic which has the highest two-week death rate in Europe.
The scheme has faced opposition from some experts who doubted it made sense as a one-off measure or pointed to the antigen tests used which are less accurate than the laboratory PCR tests and may thus return more false-negative but also false-positive results.
The government plans a second round of the testing next weekend to catch cases missed in the first round or those who got infected in the meantime.
On Sunday, Slovakia reported 2,282 new cases through PCR tests, putting the total at 59,946, without those identified in the nationwide scheme, and 219 deaths to date.